Back in the dark ages of mostly metal 35mm single lens reflex cameras, the big camera manufacturers created "kits" by packaging up reasonably fast standard prime lenses with their camera bodies. Nestled in the styrofoam box inserts, you'd also find an ever-ready case, camera strap and batteries. If you bought a kit, you saved some money over buying the lens as a separate item, the manufacturer hooked you for an OEM lens and kept you from shopping aftermarket. Win-win!
Most of these kit lenses were 50 or 55mm f/1.7, 1.8 or F/2. It would make sense that Canon, Nikon, Pentax, Minolta or Olympus would skimp on materials, assembly or optics to please the money guys, but I've yet to find one of these kit lenses that wasn't a stellar performer. Honestly, I like some of the kit lenses better than their faster and more expensive counterparts.
Of my two Olympus standard lenses, I prefer the f/1.8 Zuiko over the 1.4 version.
I really like my 50/1.8 Nikkor Ai-s lenses over Nikon's similar 1.4.
The only Canon FD lens I own is a 50/1.4 which is super-sharp and very impressive, so I am anxious to pick up the less expensive f/1.8 for comparison.
In Pentax manual focus, the 55mm f/2 and the 50mm f/1.7 lenses, at least for me, outperform the 1.4 (with exception of the M42 50/1.4 8-element SMC Takumar which is in a class by itself).
So don't shy away from the slower, less expensive standard primes of this era. They were all very well made and will deliver amazing results at affordable prices.